Automatic milking of animals is disclosed in EP-A-91 892. The automatic milking takes place in one or more combined feeding and milking stalls provided in a barn in which the animals are allowed to walk about freely and find their way individually to the stalls for feeding, drinking and milking. The animals are automatically identified in each stall and fed with the aid of a computer connected to the identification and feeding means used. By means of the computer, in which facts concerning each animal, when she was last milked, etc are stored, automatic milking is initiated. The stall also comprises retaining gates which are automatically closed to retain the animal during milking and opened to let the animal leave the stall.
Traditionally, animals are milked twice a day. Because of high labour costs it was not interesting to increase the number of milkings per day as long as milking was performed manually. It is however recognised that milking an animal three to four times a day has proven to be less detrimental to her, since the udder is not filled to its maximum between each milking. Such a milking procedure also corresponds more closely to the behaviour of the calves and therefore results in healthier animals. As a side effect, however, it is possible to increase the total milk production from one animal by 15-25%. By means of automatic milking machines it is not only possible, but would also be economically interesting to milk the animals more often than twice a day, since the labour cost is no longer critical. In this case it is rather the high investment cost which is a limiting factor.
DE-C-3 702 465 discloses a system for automatic milking and feeding of animals.
A problem of prior art automatic milking systems is their lack of reliable equipment for monitoring the animal in the stall, in order to enable immediate actions to take place in case disturbances of any kind should occur.